package com.frain.springcloud.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class SignUtil {

    protected static final Logger logger = LoggerFactory.getLogger(SignUtil.class);

    private static String token = "testFrain";

    public static boolean checkSignature(String signature, String timestamp, String nonce) {

        logger.info("  SignUtil    checkSignature ...  start....");

        logger.info(
                "signature =" + signature + "  timestamp= " + timestamp + "  nonce= " + nonce + "   token=" + token);

        String[] arr = new String[] { token, timestamp, nonce };
        // 将 token、timestamp、nonce 三个参数进行字典序排序
        Arrays.sort(arr);
        StringBuilder content = new StringBuilder();
        for (int i = 0; i < arr.length; i++) {
            content.append(arr[i]);
        }

        logger.info("  content.." + content);
        MessageDigest md = null;
        String tmpStr = null;
        try {
            md = MessageDigest.getInstance("SHA-1");
            // 将三个参数字符串拼接成一个字符串进行 sha1 加密
            byte[] digest = md.digest(content.toString().getBytes());
            tmpStr = byteToStr(digest);
        }
        catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        content = null;
        // 将 sha1 加密后的字符串可与 signature 对比，标识该请求来源于微信
        return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;

    }

    private static String byteToStr(byte[] byteArray) {
        String strDigest = "";
        for (int i = 0; i < byteArray.length; i++) {
            strDigest += byteToHexStr(byteArray[i]);
        }

        logger.info("  byteToStr method .strDigest=." + strDigest);

        return strDigest;
    }

    private static String byteToHexStr(byte mByte) {
        char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        char[] tempArr = new char[2];
        tempArr[0] = Digit[(mByte >>> 4) & 0X0F];
        tempArr[1] = Digit[mByte & 0X0F];

        String s = new String(tempArr);

        logger.info("  byteToHexStr method .s=." + s);
        return s;
    }

}
